1. Field of the Invention
The present invention relates to a method, system, and program for transferring data between storage units.
2. Description of the Related Art
In a computer system, data may be stored on one or more storage devices configured as logical units, referred to as volumes, logical unit numbers (LUNs), logical devices, etc. During system operations, the user or administrator may want to transfer data from one volume to another. One way to accomplish this task is to take the source volume offline and then copy the source volume data to a target volume. After the data transfer operation is complete, the data is accessible on the target volume.
One problem with data moving operations is that Input/Output (I/O) action is halted until the move operation is complete. If the volume being transferred is relatively large, then access to the data may be precluded for a relatively long period of time. If the volume being transferred is accessed in a network environment through a server, then numerous clients may be prevented from receiving data from the volume subject to the transfer. Further, there are likely to be more I/O requests directed to larger volumes than smaller volumes because larger volumes have more data that applications may want to access. Thus, larger volumes not only are unavailable longer to complete the data move, but are unavailable to a greater number of access requests during the data movement operation than smaller volumes.
During data movement operation, client applications attempting to access the volume subject to the move will have to delay processing until the move operation completes and the data is available. Such delays in receiving requested data may negatively impact the productivity of the client applications. Further, in network environments where access to data is critical, such as financial, medical, government, etc., such extensive delays in I/O access to a volume subject to a transfer can not only affect performance, but also disrupt operations and cause other attendant problems.
For these reasons, there is a need in the art for improved techniques for transferring data.